Lancaster, American Physical Society, 1943. 4to. In: Reviews of Modern Physics, vol 15, no. 1, p.1-89. Entire issue offered here. Original printed wrappers. Corners a little bumped. Some sunning. Else fine and clean.
First edition. This paper was reprinted in 'Selected Papers on Noise and Stochastic Processes' by Nelson Wax, Dover, 1954.